Pickproof lock



July 15, 1969 M. 1'. BASSECHES PICKPHOOF LOCK 2 Sheets-Sheet 1 Filed Nov. 15, 1967 INVENTOR. MARK T. BASSECHES ATTORNEY y 1969 M. T. BASSECHES 3,455,130

PICKPROOF LOCK INVENTOR. MARK T. BASSECHES ATTORNEY United States Patent 3,455,130 PICKPROOF LOCK Mark T. Basseches, Pleasantville, N.Y., assignor to Ilco Corporation, Fitchburg, Mass, a corporation of Massachusetts Filed Nov. 15, 1967, Ser. No. 683,166 Int. Cl. Eb 15/14, 17/00, 63/00 U.S. Cl. 70421 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention is in the field of high security or pickproof locks. Present key operated lock devices provide limited security since all or substantially all of said locks may be picked by known picking techniques.

Prior art devices intended to be pickproof have been devised. In some instances the locking devices have been so complex as to be incapable of being manufactured on any practical cost basis. In other instances the devices have become inoperative after moderate use.

Still other of such devices require the employment of keys of complex shapes, rendering duplication of the keys impossible with the equipment available to a normal locksmith.

Further and most important, many of such devices have been ineffective for their primary function-namely, to prevent picking.

A particular failure of so-called pickproof prior art locks is their vulnerability to operation by keys which, while not identical to the properly configurated key, are quite similar thereto.

SUMMARY OF THE INVENTION The present invention relates to a high security pickproof lock affording a large number of lock combinations without unduly multiplying the number of tumblers, which lock utilizes for its operation a standard type, readily duplicated key. The lock is impervious to any known picking techniques and cannot be operated by a key having a combination closely resembling the proper lock operating combination.

The device has the further advantage of being simple in its operation and including far fewer mechanical parts than lower security locks heretofore known.

The invention may be summarized as comprising a lock plug rotatably mounted in a housing, the plug having the usual keyway. A side bar is yieldably urged across the shear line defined between the plug and housing and normally lies within registering slots formed in the plug and housing, to prevent rotation of the plug. A lost motion connection is provided between the side bar and the plug, a component of the lost motion connection being interposed in the keyway and especially at the innermost end of the keyway. Lock tumbler means are movably mounted in cross bars formed in the plug at portions intersecting the keyway.

3,455,13fi Patented July 15, 1969 After insertion of a key, preferably to the entire extent thereof, the lost motion connection yieldably urges the side bar clear of its spanning position of the shear line between the plug and housing, movement of said side bar to clear the plug for rotation being blocked by the tumblers, unless the tumblers have been so oriented as to provide clearance for the side bar.

The lost motion linkage which yieldably urges the side bar into the plug operates with a limited force so that it is not possible to hang or jam the tumblers within the cross bores.

The lost motion coupling positively limits the force which may be exerted against the tumblers by the side bar, thus frustrating the most common method of lock picking, namely, applying a torque to the rotatable lock member, to exert a side pressure against the locking tumblers and oscillating the tumblers to hang the tumblers in proper plug releasing position. In other words, due to the limited force which may be applied against the tumblers by the lock bar, the tumbler springs are sufliciently powerful to force or cam their way beyond the lock bar and thus block release movement of the bar.

It is therefore an object of the invention to provide a pickproof lock, and particularly a pickproof lock of simple construction, having relatively few moving parts and adapted to be operated by a key of conventional design.

A further object of the invention is the provision of a device of the class described wherein application of a torque to the lock plug will be ineffective to interfere with the smooth operation of the locking tumblers.

A further object of the invention is to provide a device of the class described in which each and every locking tumbler must be supported at a predetermined height within the plug, as would be the case when a proper key is inserted, the existence of any unsupported tumbler precluding operation of the device.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, reference is made to the accompanying drawings, forming a part hereof, in which:

FIGURE 1 is an exploded perspective view of a device in accordance with the invention;

FIGURE 2 is a front elevational view of a device in accordance with the invention;

FIGURE 3 is a section taken on the line 33 of FIG- URE 2;

FIGURE 4 is a horizontal section taken on the line 4-4 Of FIGURE 2;

FIGURES 5 and 6 are vertical sectional views taken on the line 55 of FIGURE 3, showing the position of the lock parts respectively in the released and the locked conditions;

FIGURE 7 is a side elevational view of a modified form of tumbler suitable for use in the lock of the invention;

FIGURE 8 is a sectional view similar to FIGURE 6, showing a modified form of side bar and lock slot.

In accordance with the invention, the lock comprises a housing 10 which may be in the form of a cylindrical sleeve to be fixed to a door, an automobile dashboard, etc., the sleeve having an inner cylindrical bore 11. An inwardly opening locking slot 12 is formed in the inner periphery of the sleeve or housing 10. A lock plug 13 is rotatably mounted within the housing 10, the plug including a generally radially extending opening or clearance slot 14. A locking or side bar 15 is mounted for reciprocal movement within the plug 13, the side bar 15, in the locked position, projecting radially beyond the slot 14 and into the locking slot 12, to prevent rotation of the plug within the housing-see FIGURE 6. Preferably, the side bar 15 and the plug are provided with interfitting guide means (not shown) which prevent any tilting of the side bar about a vertical axis. In the unlocked position, the outermost end 16 of the side bar 15 is disposed within the plug 13 (FIGURE and thus provides no obstacle to rotation of the plug with respect to the housing 10.

The plug, adjacent its outer end 17, is provided with an enlarged annular shoulder 18 which bears against the end face 19 of the lock housing 10, to limit inward movement of the plug with respect to the housing. The plug is maintained within the housing against removal in an outward direction by any conventional means, such as by a lock cam 20 (see dot and dash lines, FIGURE 3), held to the inner end of the plug as by machine screws 21. It will be readily understood that any other conventional retainer means, such as a snap ring retained within an annular groove in the plug, may be employed for this retaining function.

The side bar is normally biased into the locking position shown in FIGURE 6 by a pair of coil springs 22, 23 having their outer ends 22', 23' engaged against inwardly directed shoulder portions 24, 25 defined adjacent the inner and outer ends of the side bar 15. The inner ends 22", 23" of the springs 22, 23, respectively, are biased against shoulders 26, 27 formed in the recess of the plug adjoining the slot 14.

It is an important feature of the invention that the force with which the normally outwardly biased side bar may be shifted inwardly to the interior of the lock plug is very limited and that the inward shifting movement or force aforesaid is preferably effected only when a key member is completely inserted into the keyway 28 in the lock plug. The inward shifting movement is accomplished by a lost motion connection between the plug and the side bar, and more specifically, by a bell crank assembly 20.

The bell crank assembly comprises a bell crank lever 31 which is pivotally mounted in a recessed end portion of the lock plug 13, the recessed portion being an inward continuation of the slot 14 wherein the side bar 15 is supported.

Specifically, the bell crank lever includes a central boss 32 having a vertically directed bearing aperture 33 formed therethrough. The bell crank lever is inserted into the outer end of the recess 14 and is pivotally retained therein by a pivot pin 34 which is press fit into co-axial pin retainer apertures 35, 35 intersecting the innermost end of the recess 14.

The bell crank lever includes an abutment arm 36 which is disposed at the innermost end of the keyway 28 in the path of the' tip of a key. An operating lever 37 of the bell crank is directed essentially longitudinally of the lock body. An operating spring 38 is interposed between the operating lever 37 adjacent the forward end 39 thereof and an abutment 40 depending from the side bar 15.

The springs 22, 23 normally urge the side bar 15 to the left, as shown in FIGURE 1, whereupon the' bell crank lever is shifted outwardly or clockwisely to the dot and dash position shown in FIGURE 4, such outward shifting movement being effected through the medium of the operating spring 38.

It will be observed that when a key K is inserted fully into the keyway, the tip of the key will engage against the arm 36 of the bell crank lever, inducing a counterclockwise rotation of the lever about the pivot pin 34, thus compressing the spring 38. The spring force generated by the outwardly biasing springs 22, 23 exceeds the spring force generated by the operating spring 38 in the uncompressed condition of the spring 38, i.e. when a key is not inserted in the keyway. However, after the counterclockwise rotation effected by the insertion of a key, the spring force exerted by the thus compressed operating spring 38 exceeds the combined outward biasing force of the springs 22, 23, and the side bar 15 will be yieldably urged inwardly toward the interior of the plug by a force which is a function of the amount by which the force of spring 38 exceeds the sum of the forces of the springs 22, 23.

Preferably the forces are balanced in such manner that in the inserted position of a key, the side bar is urged inwardly with a very light force. Movement of the side bar inwardly within the recess 14 to the interior of the plug assembly, i.e. to the unlocked condition, is normally blocked by a locking assembly 41 next to be described.

The illustrated embodiment of the invention comprises a series of pin tumblers 42 which are free to reciprocate within tumbler bores 43, which tumbler bores intersect the keyway 28. As best seen in FIGURES 3, 5 and 6, the tumblers 42 include upper and lower body portions 44, 45 of a diameter essentially matching the diameter of the bores 43, the body portions being separated by a smaller diameter waist portion 46. The lower portions 45 of the tumblers are of varying lengths, the length of said lower portions dictating the key combination re quired to align the waist portions 46 with the locking tongue 53 of the side bar.

The tumblers are pressed downwardly by a series of tumbler springs 47 which bear against the upper ends 48 of the tumblers, the upper ends of the springs being pressed against a retainer slide 49 which fits into a dovetail slot 50 at the upper periphery of the lock plug. It will be observed that the springs 47 press the pins downwardly so that the lowermost key engaging nose portions 51 are normally pressed against the portions 52 of the plug which define the lower terminal ends of the bores 43.

As will best be observed from FIGURE 6, the tumblers 42, in said downwardly pressed position, will present the enlarged upper portions 44 in the plane of the inwardly directed locking tongue portion 53 of the side bar 15.

As will be evident from FIGURE 6, the presence of an upper portion 44 in any of the tumbler bores 43 in the plane of the tongue 53 of the side bar will prevent the side bar from being shifted to the interior, i.e. to the unlocking position shown in FIGURES 3, 4 and 5.

It'will further be observed from FIGURE 6 that the spring arrangement whereby the side bar 15 is outwardly pressed maintains the pin tumblers 42 clear of any contact with the tongue portion 53 of the side bar. Thus, the pins 42 float within the bores 43, do not cross any shear line, and do not normally engage or rest against any portion of the side bar, etc.

When a proper key is inserted, the noses 51 of the pins will be shifted in accordance with the combination or depth of cut of the various bits of the key, as is well known. In the last thrust of the key, the lead edge of the key will engage and counter-clockwisely rotate the bell crank lever 31 in the manner previously set forth, urging the side bar 15 inwardly toward the interior of the lock plug under the influence of the operating spring 38. It will be observed that the downward force exerted by the pins 42 acting against the key bits in the final stages of insertion of the key tends to force the key inwardly toward the arm 36 of the bell crank lever, and thus there is no tendency for the key to become unseated. If all of the narrow waist portions 46 of the pins are aligned so that they are precisely at the same plane as the tongue 53 of the side bar at the instant the side bar is shifted inwardly by the bell crank, the side bar will be permitted to shift inwardly to the position shown in FIG- URE 5 under the influence of spring 38, thereby freeing the plug for rotation.

If an improper key is inserted, rotation of the bell crank lever and the consequent application of an inward force to the side bar will be ineffective to unlock the device, since the side bar will be prevented from inward movement by the enlarged portions 44 or 45 of any unaligned tumbler pin.

It will be readily appreciated that the invention is not restricted to use with pin tumblers, but that plate tum blers, disk tumblers or any other means which blocks the movement of the side bar may be substituted. Where pin tumblers are used, it may be desirable, as shown in FIGURE 7, to utilize one or more false shoulder portions F on the side of the pin adjacent the unlocking or deepest grooved portion so as to avoid any possibility of a pin inadvertently being supported at a proper unlocking position. For master keying, a plurality of deeper grooved portions may be provided on one or more of the tumblers.

It will be readily recognized from the foregoing description that the lock of the present invention will frustrate any known picking techniques. All of said techniques are predicated upon the application of a lateral force against the tumblers or other locking mechanism and the simultaneous lifting and dropping of the tumblers. A skilled lock picker, by this means, is enabled, by the application of such lateral force against the pins, to hang the pins at the proper height to which the pins would be lifted by a correct key.

The present device frustrates such picking techniques in a plurality of ways. First, the amount of lateral force which may be exerted against the sides of the pins is limited and controlled precisely by the balance between the outward and inward forces developed by the side bar springs and the operating spring. Thus, such a limited amount of force is exerted against the sides of the pins that the pins may readily pass beyond the side bar even if a pressure is maintained against the bell crank lever.

Second, in view of the very limited lateral forces which may be exerted against the pins, the downward forces which urge the pins to their lowermost position may be adjusted to be sufiicient actually to cam the side bar outwardly and permit a pin to pass downwardly beyond the inwardly urged side bar.

The importance of this feature of the device will be readily appreciated when it is observed that most lock picking techniques are predicated upon operating the lock with the locking pins within the plug unsupported by any key.

In a typical example of a pin tumbler lock wherein the junction between the upper and lower pins in the unlocking position is aligned with the shear line, the picker will apply a lateral force to the pins by twisting the plug to displace the cross bore portions of the plug and housing, and thereafter oscillate the pins, to hang the upper pins on the periphery of the plug, in which position the plug may be rotated. In this condition, the lower pins are unsupported and present no obstacle to the rotation of the plug.

As explained above, the lock of the present invention may not be operated when a pin is unsupported since, as soon as pressure beneath a pin is released, it will shift past the side bar, to maintain the same in a locking position.

In a more advanced and difiicult form of lock picking, the picker laboriously senses the proper height of the pins by oscillating the pins up and down while applying a torque and noting at what height each pin exhibits the greatest resistance to oscillation. The picker then, in effect, creates a key in accordance with the heights sensed. The device of the present invention, particularly where a tumbler pin as shown in FIGURE 7 is employed, will frustrate even this complex picking method since the only heights which may be sensed by oscillating the pins are the heights defined by the lowermost and uppermost edges of the enlarged portions 44', 45', respectively. The picker sensing these heights will not be able to construct a workable key therefrom.

Obviously, the number of false or enlarged portions may be multiplied so that a plurality of wide waist grooves are disposed along the length of the tumbler pin and only one narrow or releasing waist portion provided.

In FIGURE '8 there is shown a fragmentary view of an embodiment of the invention having a further means for frustrating picking of the lock. In this embodiment, the

locking slot 12' is dove-tail in shape, including sharp end portions 12". The lock bar 16 in this embodiment includes a longitudinally extending recess or recesses 60 along its upper and lower edges. The recess incorporates a central, outwardly directed lug 61, the lug being spaced from the end of the side bar a distance which will align the lug just inwardly of the toothed portions 12" when the bell crank lever is actuated by the insertion of a key or pick tool and the inner end of the side bar engages against the enlarged diameter portions of the pins.

It will be observed that in this condition if any torque is applied to the plug, the cam angle defined adjacent the tooth portions 12" will engage the innermost end of the lug 61 and tend to cam the side bar outwardly away from the pins. Also, the engagement of the tooth and lug will prevent the side bar from being drawn inwardly until the plug is rotated to a central position, at which position any possible pin hanging effects resulting from the application of torque will have been dissipated.

From the foregoing it will be seen that there is described a high security lock device which, in addition to being pickproof, is of simple construction, requiring a limited number of moving parts.

Since the pins of the present device do not extend across the shear line, it will be readily recognized that the task of disassembling the plug from the housing will be greatly simplified. Thus, re-combinating the lock is a simple process.

Also, since the pins are disposed entirely within the plug, it will be understood that the lock is more impervious to weather conditions than is the case in conventional locks wherein the pins cross a shear line and wherein it is possible for moisture and detritus to enter the lock mechanism through the exposed shear line.

Having thus described the invention and illustrated its use, what is claimed as new and is desired to be secured by Letters Patent is:

1. A lock device comprising a housing having a bore, a cylindrical lock plug rotatably mounted within said bore and having an axially extending keyway, a plurality of cross bores formed in said plug and intersecting said keyway, a clearance slot extending inwardly from the periphery of said plug and intersecting said cross bores, a lock bar member mounted in said clearance slot for reciprocal movement, a lock slot formed in said housing in registry with said clearance slot in the locked position of said device, lock spring means interposed between said bar member and said plug and yieldably urging said bar outwardly of said plug to project portions of said bar into said lock slot, tumbler means reciprocably movable in said cross bores, said tumbler means including bar blocking and bar unblocking portions, tumbler spring means in said cross bores for yieldably shifting said tumbler means in said cross bores normally to align bar blocking portions of said tumbler means with said clearance slot, and retractor means in said keyway operably connected with said bar member for urging said bar member inwardly of said plug responsive to the insertion of a key into said keyway.

2. A device in accordance with claim 1 wherein said retractor means and said bar member are connected by a lost motion linkage.

3. A device in accordance with claim 1 wherein said retractor means comprises a lever member disposed in the path of a key inserted in said keyway and shifted out of said path responsive to insertion of a key.

4. A device in accordance with claim 2 wherein said lost motion linkage comprises retractor spring means interposed between said lever member and said bar member for biasing said bar member inwardly of said plug, the inward biasing force of said retractor spring means exceeding the outward biasing force of said lock spring means when a key is inserted in said keyway.

5. A device in accordance with claim 1 wherein said slot and bar include complemental tooth and recess portions shifted into engagement responsive to the application of a torque to said plug in the locked position thereof. 6. A lock comprising a housing having a bore, a plug rotatably mounted in said bore, lock means in said plug shiftable toward and away from said housing, spring means yieldably urging said lock means into said housing, thereby to lock said plug and housing against relative rotation, blocking means in said plug in the path of said lock means for preventing movement of said lock means away from said housing, first release means communicating with a keyway in said plug for yieldably urging said lock means away from said housing responsive to insertion of a key in said keyway and second release means in said keyway for shifting said blocking means from the path of said lock means responsive to insertion of a key in said keyway.

7. A look comprising a housing defining a bore, and a recess opening onto said bore, a lock plug rotatably mounted in said bore, a lock member movably mounted in said plug, first spring means yieldably urging said lock member into said recess of said housing with a first force, second spring means in said plug for urging said lock means out of said recess with a second force less than said first force, tumbler means in said plug for blocking movement of said lock member out of said recess and key means insertible into a keyway in said plug for shifting said tumbler means from blocking position of said lock member and means in said keyway cooperating with said key means for compressing said second spring means to increase said second force to a value greater than said first force.

8. A look comprising a housing having a bore, a plug rotatably mounted in said'bore and having a keyway, movable lock bar means extending across the shear line defined between said plug and housing, said bar being shiftable between unlocked shear line clearing and locked shear line intersecting positions; tumbler means in said plug blocking movement of said lock bar from said locked to said unlocked position, and lost motion connector means interposed in said keyway for yieldably urging said bar toward said unlocked position responsive to insertion of a key in said keyway.

References Cited UNITED STATES PATENTS 2,426,104 8/1947 Johnstone 421' 2,879,658 3/1959 Johnstone 70364 2,949,762 8/ 1960 Johnstone 70364 3,035,433 5/1962 Testa 70364 MARVIN A. CHAMPION, Primary Examiner R. L. WOLFE, Assistant Examiner U.S. Cl. X.R. 

